Safety device for a projectile



Dec. 11, 1956 L. A. B. KARSBERG 2,773,449

SAFETY DEVICE FOR A PROJECTILE Filed Feb. 10, 1955 2 Sheets-Sheet 1 Fig.1

Arro AWE) Dec. 11, 1956 Filed Feb. 10-, 1953 Fig.2

| A. B. KARSBERG 2,773,449

SAFETY DEVICE FOR A PROJECTILE 2 Sheets-Sheet 2 VIII/Ill J'NvE/VraR ZamflA/one: 8/20 Mani/ea 1 nited States SAFETY DEVICE FOR A PROJECTILE Lars Anders Birger Karsberg, Karlskoga, Sweden, assignor to Aktiebolaget Bofors, Bofors, Sweden, a corporation of Sweden The present invention relates to a safety device for a projectile.

Such a safety device must on one hand with reasonable certainty prevent an accidental or premature detonation of the projectile. On the other hand, it must with equal certainty assure that the projectile is armed at the appropriate time.

The principal object of the present invention is to provide a novel and improved safety device which affords a high degree of safety and also assures arming of the projectile at the desired time.

Another object of the present invention is a novel and improved safety device of the general kind above referred to, which includes two arming members both held in a safety position until it is desired to arm the projectile and simultaneously released for movement into the arming position. The provision of two arming members doubles the likelihood that the projectile is safely retained in its unarmed position, but actually armed when required.

The present invention will be described more in detail in connection with the drawing Where Fig. 1 shows an isometric view of a safety device according to the present invention, some of the components being shown as if they were transparent for sake of clarity of the illustration and Fig. 2 shows an isometric section of the safety device.

In the figures, 1 is a cylindrical member. The reference number 2 shows the wall of a projectile, in which the member 1 can be arranged. The cylindrical member 1 includes three parallel holes 3, 4 and 5. The holes 3 and 5 are identical. One end of these two holes is provided with threads 6 and 7, respectively. In each of these ends is screwed a plug 8 and 9, respectively, provided with threads. The said plugs are each provided with an axial hole. The hole of plug 8 is visible in the Fig. 1, and has been given the reference number 10. In each of these holes one end of a spring 11 and 12, respectively, rests. The other ends of the springs 11 and 12, respectively, rest in a reces in one end of cylindrical arming members 14 and 15, respectively. The recess in the member 15 has been given the reference number 13. The members 14 and 15 are provided with peripherical grooves 16 and 17, respectively, which preferably have slanting walls. In these grooves, part of the balls 18 and 19, respectively, rest. The rest of the balls are in a hole 20 extending through the member 1, transversely of the holes 3-5. In the said hole, two bars 21 and 22 are arranged. These bars rest with one end each against the balls 18 and 19 and with the other ends against a member 23, and then against two bevelled surfaces of this member. The member 23 is fastened at one end to a spring 24. One end of the said spring is fastened to a screw 25 arranged at the hole 4. At the other end of the member 23, a loop 26 is fastened. Through this loop 26, an incandescent filament 27 runs, the ends of which are fastened to the contacts 28 and 29 mounted on a plate 30, which is arranged in a hole 31 of the member 1. The end contacts 28 and 29 are preferably connected atent O 2,7 73,449 Patented Dec. 11, l

to a voltage source. The non-spring-actuated ends of the two members 14 and 15 are provided with slots 32 and 33, respectively. These slots engage the bar 34 and 35, respectively, arranged in holes 36 and 37, respectively. These holes are perpendicular to holes 3 and 5. Furthermore, the two members 14 and 15 have transverse holes 38 and 39, respectively, which contain a charge each, one of which is visible in the figures, and is marked 40. In the member 1 there are also provided two transverse holes movable into registry with the holes 38 and 39. Only one of these holes is shown in the figures, and has been marked 41. These two last-mentioned holes are intended to function as guides for striking pins. In the figures, one such striking pin 42 is shown in the hole 41. In case the device described above is to function as a safety device for projectiles with hollow charges, the charges in the holes 38 and 39 will be omitted as well as the said striking pins.

The device described above functions as follows. Let it be assumed that the two members 14 and 15 are in the position shown in Fig. l, i. e. in the hooked-up position. The balls 18and 19 rest in the grooves 16 and 17. They are kept pressed into the grooves by means of the bars 21 and 22. This retention is caused by the other ends of the bars being separated from each other by the aid of the member 23. In this position, the holes 38 and 39 will be out of line with the hole 41 and the corresponding hole of the member 141 If in this condition a voltage is supplied to the contacts 28 and 29, the incandescent filament 27 will be heated so that it will break. Thereby, the spring 24 will withdraw the member 23 from engagement with the bars 21 and 22. On account of the members 14 and 15 being springactuated and because of the design of the grooves 16 and 17, the balls 18 and 19 will be pressed out of the grooves, and the members 14 and 15 be enabled to move freely. The members will now move into a position such that the ends of their slots will engage the bars 34 and 35. In this position, the members 14 and 15 will be kept at a standstill. The holes 38 and 39 will form a continuation of the hole 41 and the corresponding hole in the member 14. The safety device is now unlocked. One or both of the striking pins can now function, whereby an actuated charge will create a flash. If the safety device has instead been intended for a projectile with a hollow charge, each of the holes 38 and 39 would have formed a passage for flames when the device was unlocked.

I claim:

1. A safety device for a projectile comprising a generally disc shaped base having two transverse bores and a third bore extending between said two bores, an arming member fitted in each of said transverse bores axially slidable between a safety position and an armed position and spring biased into its armed position, each of said arming members being formed with a circumferential groove situated in alignment with said third bore when the arming members are in the safety position, two lock bars disposed axially slidable in said third bore, the distal ends of said barscoacting with said grooves for locking the arming members in the safety position and the combined length of the bars being such that in the groove coacting position thereof the juxtaposed ends of the bars are spaced apart, a safety control member mounted for movement between a position filling said space between the respective bar ends for retaining the bars in the locking position and a position withdrawn from said space to release the bars from coaction with the grooves for movement of the arming members into the armed position by spring action, and release means for movement of the safety control member into its withdrawn position,

2. A safety device according to claim 1, wherein wall portions of the arming members defining said circumferential grooves are slanted relative to the direction of the axial movement .of said lock bars for ejecting the said bars from coaction with the grooves by the spring pressure acting upon the arming members when the latter are freed by release of the lock bars.

3. A safety device according to claim 1, wherein the said base has a fourth bore disposed intermediate of said two transverse bores and issuing into said third bore adjacent to said space formed between the respective ends of the lock bars, the said'safety control member being in form of a rod axially slldable in said fourth bore.

4. A safety device according to claim 3, wherein lock balls fitted in said grooves are interposed between the respective ends of said lock bars and the arming members, the said third bore being extended at each end beyond said transverse bores to provide space for entering of the balls upon, release of the lock bars.

5. A safety device according to claim 1 and further comprising stop members fitted in said transverse bores and disposed to arrest the arming members in the armed position against said spring action acting upon the arming members.

6. A safety device according to claim 1, wherein the said safety control means comprise a rod mounted slid- 4 a ly r l t e t sa d lock ar an spring bia ed into i position withdrawn from the respective ends of the said bars, and wherein the said release means comprise a breakable element secured to said rod and the base for retaining the rod in its position between the respective lock bar ends and spring means moving the rod out of said position upon breaking of said element.

7. A safety device according to claim 6, wherein the said breakable element comprises a filament destructible by a rise of temperature due to an electric current flowing through the filament,

8. A safety device according to claim 1, wherein the said arming members are movable by the spring action in opposite direction through an equal distance and at equal s eed, he s d mo men hro gh n qual d tance and at an equal speed moving the arming members simultaneously into the armed position.

References Cited in the file of this patent UNITED STATES PATENTS i i ammwmm 

